@article{ZNSL_2004_308_a1,
     author = {V. M. Babich},
     title = {On $PC$-ansatz},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {9--22},
     publisher = {mathdoc},
     volume = {308},
     year = {2004},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2004_308_a1/}
}